Update buying_controller.py
diff --git a/erpnext/controllers/buying_controller.py b/erpnext/controllers/buying_controller.py
index db1c44e..0dde898 100644
--- a/erpnext/controllers/buying_controller.py
+++ b/erpnext/controllers/buying_controller.py
@@ -696,7 +696,9 @@
if not self.get("items"):
return
- self.schedule_date = min([d.schedule_date for d in self.get("items")])
+ earliest_schedule_date = min([d.schedule_date for d in self.get("items")])
+ if earliest_schedule_date:
+ self.schedule_date = earliest_schedule_date
if self.schedule_date:
for d in self.get('items'):